My invention relates to a mechanism for adjusting the angle of the worksurface of a desk or workstation. This invention also relates to an adjustable desk-top assembly having an improved lift mechanism for facilitating adjustment of the angle of the worksurface of the desk or workstation in accordance with the desires of the user.
Desks have evolved from simple table-like structures into some fairly complex designs. One example of such a design is illustrated in U.S. Pat. No. 4,646,655 to Robolin for a Data Processing Work Station. In the assembly of Robolin, a tubular framework is provided having multiple shelves for holding various components of a data processing system. Another assembly is described in U.S. Pat. No. 4,561,619 to Robillard et al. for a Movable CRT Pedestal. This assembly involves the use of a laterally movable support for a video display monitor. The support includes telescoping arms for adjusting the distance of the monitor from the user.
Other desk designs involve the use of slanted and/or wraparound worksurfaces. Such designs are exemplified by U.S. Pat. No. 744,888 to Widman et al. This patent discloses an office desk with a slanted worksurface having a recessed central portion so that the desk wraps around the user. Another example is found in U.S. Pat. No. 1,293,952 to Shirley describing a desk featuring a wrap-around design with storage compartments.
Many of the known designs are disadvantageously limited to specifically defined applications. For example, a desk designed for a data processing station may lack a writing surface. Other desk assemblies are unable to accommodate a computer system, or do not facilitate convenient use of a keyboard without difficulty.
In order to overcome the drawbacks of known desk assemblies, an adjustable desk-top assembly has been developed which can support a variety of functions and can be supported by a variety of means. Such a desk-top assembly is described in U.S. Pat. No. 4,781,126 to Lochridge, the disclosure of which is herein incorporated by reference. The adjustable desk top can serve as a data processing station with storage capabilities, as well as a writing or drawing worksurface which is convenient and comfortable to the user. The assembly described in U.S. Pat. No. 4,781,126 provides an exemplary separate supporting desk top wherein the worksurface is adjustable to assume different slopes to suit the user.
FIG. 1 of the present disclosure illustrates a desk-top assembly 10 of U.S. Pat. No. 4,781,126, having a desk pedestal 12 a base or lower panel 16 and an upper panel 22. The assembly 10 shown in FIG. 1 includes one type of mechanism for adjusting the position of desk top 28 about a pivot point. A securing means 35 having a bar 36 secured by brackets 38 near the front edge of the desk-top worksurface 28 provides the pivot point. The ends of the bar 36 are secured within the assembly via apertures or slots formed near the bottom portion of side panels 26. A spacer block 42 is disposed beneath the back edge of surface 28 for adjusting its elevation relative to the base member 16. By adjusting the position of the spacer 42 forwardly or rearwardly beneath the back edge of surface 28, the slope imparted to the worksurface is varied from about zero to 45 degrees inclination.
A second type of lift mechanism for adjusting the tilt of a desk top is shown in FIG. 2. In the assembly of FIG. 2, a transverse support bar 52 is secured to extend between the right and left sides of base member 16. Extending upwardly through the bar 52 is at least one jack screw 54 disposed for axial movement. A bracket 56 is secured to the underside of the bar 52 for securing a pulley 58. Each jack screw 54 is threadedly engaged by a pulley 58, with the pulleys being interconnected through a cable 60. Cable 60 extends around each pulley 58 and around an additional pulley operatively connected to a motor 64 for moving the arrangement. The motor 64, connected via power cord 68 to a power source, is mounted inside a compartment on base 16 and has a shaft 66 extending downwardly therefrom to fixedly engage and turn the additional pulley. This in turn causes each pulley 58 to rotate, thereby moving each jack screw 54 in a vertical direction. The vertical movement of the threaded jack screw 54 serves to adjust the slope of the surface 28 to the desired level.
While the above-describe mechanisms for adjusting a desk top adequately serve their purpose, in using the first mechanism the user may be required to remove objects from the desk top, and then move the spacer beneath the desk top to adjust the tilt. The second lift mechanism requires the use of pulleys and cable, which may suffer from wear after extended use.
Other lift mechanisms for adjustable table tops are known in the art. U.S. Pat. No. 1,171,523 to Kuhn discloses a Drafting Table adjusted by means including hinged arms which swing upwardly and downwardly. U.S. Pat. No. 1,293,246 to Thompson describes an adjustable desk or table having guide bars hingedly connected thereto. U.S. Pat. No. 1,829,288 to May relates to a Drafting Table having means for adjusting the inclination thereof, which include pivotally connected links having a slot and a clamping bolt. U.S. Pat. No. 1,837,826 to Mitchell et al. describes a Vertically and Angularly Adjustable Table having two systems of crossed links arranged in parallel vertical planes extending from front to rear of the table. U.S. Pat. No. 1,921,489 to Stein discloses a Cutting Table pivotally mounted, having means for locking the table in a horizontal position. U.S. Pat. No. 2,844,908 to Moore describes an Adjustable Drawing Easel having a pair of extensible elevating arms pivotally adjustable via carriage bolts engaged in slots. U.S. Pat. No. 3,492,952 to Yourist discloses a Portable Drawing Board having pivotable frames hingedly connected to each other.
A more recent type of adjustment mechanism is illustrated in U.S. Pat. No. 3,605,650 to Hebel et al., disclosing a tiltable Drafting Table having pivot pins which extend from the sides of the table top and engage a frame. The frame includes support sleeves for engaging the pivot pins, and arrestor guides may be provided for locking the table top in position. Another recent mechanism is shown in U.S. Pat. No. 4,474,115 to Carlton, describing a Tilting Table wherein an adjusting knob actuates a threaded horizontal shaft which actuates a linkage arrangement to adjust the position of a table top.
While the prior art contains various types of lift mechanisms for raising and lowering a table or desk top, the mechanisms suffer many disadvantages. For example, many of the mechanisms are bulky, cumbersome and inconvenient. Some prior art mechanisms cannot operate smoothly when bearing a significant amount of weight, while others cannot support a significant load, such as 350 lbs., throughout the various angles of inclination. Other mechanisms are subject to wear and weakening upon repeated use. Further, various prior art mechanisms suffer from the drawback of not being conveniently and reliably lockable. Additionally, some of the adjustable worksurfaces of the prior art are expensive to produce, while others are difficult to install and/or service.
Accordingly, a reliable lift mechanism is desired having advantageous features for conveniently and effectively adjusting the angular position of a worksurface, desk top, table top or other surface in a practical manner.